Downloaded a character model that has a skeleton but need help so i can pose it
It seems that the rig and the model were created by another 3D software and have been imported to Blender. I doubt that this rig works well in Blender, but to answer you question first. 


In Object Mode Select the model RMB
Select the rig Shift-RMB
Ctrl-P With automatic weights 


The bones shape can be changed in the properties panel:



For your first steps I would recommend to find another model that meets the blender conventions. Or use the rigify addon to create your own rig.